Issues with display flickering and checkering

Hi! My girlfriend has a model A1278 mbpro and was recently watching a movie on it. All of the sudden, a grid of checkers that sometimes flicker and flash different shapes appeared and take up the entire screen. Any idea as to what is causing this? I've read its most commonly a video card issue and wanted to see if anyone had any input. Also, when I boot in safe mode the problem is corrected. THANKS!!